Stochastic synaptic plasticity underlying compulsion in a model of addiction

Area of Science:

• Neuroscience
• Addiction Research
• Behavioral Science

Background:

• The mesolimbic dopamine system reinforces behaviors, but chronic overstimulation, such as in drug abuse, can lead to compulsive intake.
• Understanding the neural mechanisms driving compulsive drug seeking is crucial for developing effective addiction treatments.

Purpose of the Study:

• To investigate the neural circuits underlying compulsive reinforcement in a mouse model.
• To identify specific brain regions and synaptic changes associated with persistent drug-seeking behavior despite punishment.

Main Methods:

• Mice were allowed to optogenetically self-stimulate dopaminergic neurons, with some experiencing punishment (electric shock).
• Activity in orbitofrontal cortex (OFC) to dorsal striatum projections was monitored.
• Synaptic plasticity (potentiation and depotentiation) in this pathway was manipulated to assess its causal role in compulsive behavior.

Main Results:

• Compulsive lever pressing, indicative of addiction-like behavior, correlated with heightened activity in OFC to dorsal striatum terminals.
• Permanent synaptic potentiation in the OFC-striatal pathway was observed in mice exhibiting compulsive behavior.
• In vivo manipulation of this synaptic potentiation causally induced compulsive lever pressing, while depotentiation reversed it.

Conclusions:

• Synaptic potentiation of transmission from the orbitofrontal cortex to the dorsal striatum is a key driver of compulsive reinforcement.
• This finding provides a specific synaptic mechanism underlying a core symptom of addiction.
• Targeting OFC-striatal synaptic plasticity may offer a novel therapeutic strategy for addiction.